Telephone system



6 192 Sgpt 7 J. H. L Evls, JR

TELEPHONE SYSTEM Filed Sept. 16. 1925 E! PDO MAES E. J N Y v E R E N O L U R T O .EDUM DMOU XML om W N T N H A Mv I .w A xu 0520.54 .\m- Z22 Pr Y B bm MUZIQQLUXH Patented Sept.` 6, 1927.

UNITED sm'frss .PAT

ENT kerr-ics.

JOHN H. LEVIS., JR., OF ROCHESTER, NEW YORK, ASSIGNOR TO THE STROMBERG- CARLSON TELEPHONE MANUFACTURNG COMPANY, OF ROCHESTER, NEW YORK,

`.A CORPORATION OF NEW YORK.

TELEPHONE' SYSTEM.

Application filed September This invention relates to telephone systems and more particularly to small exchange systems, which cooperate with a main telephone system.

In private branch exchanges, such as are used in offices and apartment houses, there are certain conditions, which must ce met in order to give efficient service, when such branch exchanges function withmain automatic exchanges.`

Among the greatest difliculties encountered in operating a private branchexchange in connection with a main automatic exchange is that known as false preliminary impulses. It is well known that in an automatic exchange the automatic switches are operated by a series of line interruption varying in number in accordance with the desired connection; it, therefore, becomes necessary when a private branch exchange is connected to a main automatic exchange to obviate all line interruptions, except those originating from the dial sendei at the private branch exchange.

Also when private branch exchanges, which were 'designed to connect with `inanual telephone exchanges, are to be used in connection withv automatic exchanges, the cord circuits of said private branch exchanges must be reorganized for usel in thenew system.

The main feature of the presentv .invention resides in the novel arrangement of circuits 'for a private branch exchange, which will function with a main automatic exchange without introducing false preliminary impulses into the system.

Another feature of the invention resides in the designs of cord circuits for a private branch exchange,which are adaptable lfor use in connection with manual or automatic telephone systems.l

Other features of the invention will appear from the detailedV description and appended claims.

'.ln the drawing there is indicated at the left, a private branch exchange telephone line of which there are a plurality. In-the center of the drawing there is indicated diagrammatically, one kof a plurality of cord circuits of which there are `Vseveral, while at the top of the sheet there is diagram- 16, 1925. Serial No. 56,758.

matically indicated a dial sender, andy an operators telephone set, which lmay be connected to any of the cord circuits. At the right of the drawing there is indicated a second private branch exchange line, while at the extreme lower' left and at the extreme lower lright,.there is indicated a portion of a trunk circuit, which connects with a main automatic telephone system. f

It is believed that the invention will best be understood by describing the method of completing the different types of calls which may be extended through the system.

@all from P. B. X. Zinc to mot/ier P. E. X. Zine.

When the subscriberat A initiates a call by removing his receiver from its switchhook, the line relay 5 is energized over the two sides of the calling line in series and through the contacts of the cut-off relayG, to grounded battery, in the well-known manner. The energization of the line relay 5 lights the line lamp 7 to signal the operator that a line is calling. The operator then inserts the plug P of an idle cord circuit in to the jack J of the calling line. At this time Vthe various keys are in the condition indicated on the drawing, so that the sleeve relay 8 energized from grounded battery, its winding, contacts 9 ofthe thru dialling'lzey, sleeve contacts of the plug P and jack J, winding of the cut-off relay 6 to ground. kSleeve relay 8 and the cut-off relay 6 are energized in this circuit. The sleeve relay on operation connects the answering supervisory relay l0 to the answering end of the cord circuit for the purpose of providing supervisory means in the form of a lamp ll. rEhe connection of the supervisory relay l0 to the answering end of the cord circuit, results `in its energiZat-ion and at its `armature and back Contact opens the lighting circuit of lamp ll, which is otherwise completed at one point at the lower front contact andarmature of relay 8. The energization of the cut-off relay 6 disconnects the fline relay from the calling line, therevby permitting -it to deenergize and extinguish the line lamp 7. rhe 'operator thereupon connects her telephone set (not shown), by ymeans of conductors l2 and 13 and the rentuete the answering end ot the eord eireuit. whieh i5 eoiineeted to the culling; telephone line. Vin nipiirhugy :tor u 1d reeeiring the lerne uutiou of the, u'unted line. .s'ueh :te ll, the operator inseVI rz the fulline plug` l. olf the cord eireuil. into the jueli d ot the Wunl'ed line. rthis rem-ulti in the energizution ot the sleeve rel-.15v lo in u e'reult tueeuhle :l'roni grounded buttery, its winding. eondurtor .l eontuet l oit the thru diulliii'ij.;1 key, eonduetor ll), bileere eontuetn ot the plug' l und juehV J', winding` ol the eutolli relzrxY El) to ground. 'llhe rutolt relu)Y tl is energized ut. this time to dineonneet the line 'relug` 2t troni the culled line. whit-.h prewuitw` the lighthu;l olf the line lmnp i2 when the euiled purty un r\\'er.-;. the sleeve. relu)Y lll ou energimtiou eonueets the ruil ine; superriuory reluy 25? to the rullini! end et the oord.l whirh permits` r-:uperriuiou ou tliiiel end, o t the eord. hy uieun` ol' the imper- VisoriV lump 'Vlhe operutor thereupon depre:- =;u the ringing hey und elofies u eireuit thruiurh the eontuetu .l und it, Atroni the Fourre. o i,E ringriur` euri-ent over the eullingf end ot the oord eireult und the eulled line with the indistullou ruil eign-lil inelnded in series 'therewith1 the Subset lier nl' sulwtniion 'l on noting;l this siguul reiuiwes lli@ rereirer Ytroni its iuritelrlioolr, n'hieh eeuujiletefl. e.

l--l und l5 ol the listening' het' 'lo dneet eurrent pznh troni ground und grounded liuttetuY through the two windine'u ol' the "ulliug Vl"upl-ir\isoif\* relay Q3 und the eontnets oit the @leere relujf lli through the two sudeu ot the Aidling end ot the eord eireuit und the eilled line in series. lhis energize-s relayv LESS und zu its lower urinature und trout eontuet, elosee u eireuit tor netuuting; the relay Whieh eireuit is completed nt the lowerniost :liront eontuet und mnuiture ot relu \v lo. llelur L when energized in thiss eireuit. :it its; upper Ylront eontuet und uriiuituro` eloses. u luelciugr eireuit 'lor ilsell. Vindopelulent ol the rontrol ot rel-uy Q. lelur if; inet'- lerlire ut this, time.

litt the elorie oll the conversation. when the telling suhseriher replnee4 hir: reeeirer on its nu'itelrluiol. the answeringl Supervisory relu)v lll. luis itS operating' eireuit opened und thereiuuiu deeuerggjiues. This rez-Iults in the liplitiiity ul. the ul'iperfisory lump ll.. lrorn huttery. lhrturoh this lump. heel: eontuet und uruiuture ot the relujf 10. lowsiu'iuout 1li-ont eontuet und urnutlure of relay ll to ground. ll'hen the e; lied SluliSeriher replzu'eslhie rereiter on the Switch-hook, the enllinpT Suiperrir-Lory reluy 2&3 hun itzI operating eireuit opened und ulso deeuergixes. This reiiulte in the lighting' ot the rolling ruperrisory lunip trom grounded huttenr througrh this lump. lower heel: ront-.zet und urn'mture et relug' 22E. 'lront eontnet :and nrniutnre of relay lti to ground.

'lfhe operutm: on noting` tluit these linups ure hoth lighteth removes the plugs l und l iti-ozu the juries with whleh they have been in engagement. .lhiu relsulls in the deenergizution ol the .Sleeve relojes t5 :und lll, which rezforer the equipment to iti:` nornrul eonditieu. lt will he noted thut :1. ringlmelt key i. who rn in. eouneetion with. the answering end ot the cord. eireuit und provided ilor use whenever the :inheerilier asks the P. B. operator to ring` o. special nuinher und then will him hue-li when the culled party is reuehed. lfnder sneh u condition, it .is not iuuef;-.=ur.\j lo remove the answering plug l) Vlroru the juelt ol'A the enlling line.A lu'lt when the. eulled purty irl found, the. ring-bueh hey Yil'. eperuted to uppl)v Signalling eurrent to the milling; lire, us u result olf n'heh the ,Linlireriher remotes his receiver il'roin the switchhoolt und proeeedu with the eull.

teruuuuleu :it nu uutoniute exchange (not uhou'n) desires to ext end u. telephone eonnee tion lo u line .Queh :is llrul deeigi'xuted l5, he 'eniures hir; receiver 'troni its uwiteh-hook und ope ailes the, diul Hendel' :uesoeiu ted with l.- line tul zo not shown), to trunsnlit sew o il eerie-s oli impulses` eorreslionding to the designntion ot the pi-irate lu'uneh exehunge line. ln refuionle lo these reries: ol impulses uutoinutio switrhes (not uhown) extend the milling line to the trunl; eirenit7 the eoudur tors ot whieh nre deeignuted 2b. ln ueeordunee with the operution o'l this uuto inutie erpiipuieut, utter the seizure ot the trunlii "m ringing' eurreut is upplied over the two elders ot the trunk und the oonoi" `incl; J2 through the lett hund Windw J ot the reliry ill). Thin relugr .is so de- ;Xned lhzu il. reupondri to this ulternuting rurriuit und :uit 'uetu itu uriuuture to light the trunlf; lzunp lll). Un noting that luinp I3() iu lighted the oper: tor limertu the plug` l ol un idle eord eli-enit into the jack J und since the sleeve, ot the jock J hue no potentiel thereon. the sleeve relay 8 not energized. with the reeult that the unswering: fuiperrisory reluY lll its not operated as in the euse olf u loezd erll. The insertion o'lv the plug l) into the trunk jock, however, eonipletes u eireuit :troni the upper Side ol" 'the trunk Qt through the tip eontnel'el ol. the jurk l2 und the plug' l?. through the eontues ot the ringdiuelt key, upper urine`I ture und hut-li eontuet ol the sleeve. relay 8, eontnets ill ot' the. thru diul key. windingot the reluy inner huelt eontuetund :trinitture ot reliijg7 8, eontzufts,y 3255 ot the lust nientioned hey. over the lower Side oit the an snoring eord und the lower side ol.2 the trunk to the uutonmtie exchange. At that exchange, the eireuit is completed lull lilo

through grounded battery, so that the relay is operated tor a purpose to be described.

The operator thereupon depresses yher listening key to connect her telephone set through contacts 14 and 15 of this key to the mentioned cord circuit and inquires the number of the wanted line over the portion of the connection thus far completed. On ascertaining thatrthe wanted Jline isy that indicated at B, the operator inserts the plug P into the jack J t and-then depresses the ringing key to apply ringing current to the wanted line. Then the called party responds by removing his receiver trom its switch-hook, the supervisory relay 23 is operated in the manner already described.

On the operation of this relay, the relay 27 is energized from grounded battery, its winding, inner front contact uand armature ot relay 23, front contact and armature of relay 16 to ground. Under this condition of the circuits, when the called party terminates the connection, by replacing his receiver on its switch-hook, the supervisory relay 23 deenergizes and thereby completes a circuit from ground, armature and back contact of relay 23, the supervisorylamp 24, to grounded battery and in multiple therewith through the armature and front Contact ot relay 27, conductor 34, lower armature and front yContact of relay 32 and thence through the answering supervisory lamp 11 to grounded battery. On

Anoting that the supervisory lamps 11 and y 24 are lighted, the Aoperator removes plugs P and P from the jacks with which they have been in engagement, with the result that the cord circuit equipment reverts to its normal condition.

@all from private branch emo/omge to automatic main.

Let it be assumed that a subscriber, such as A, at a private branch exchange desires to obtain a connection to a subscriber' whose line terminates at a main' automatic exchange. The calling subscriber initiates a call in the manner previously described,iby removing hisreceiver fromits switch-hook,

which results in the lighting of the line` lamp 7. The operator then inserts the plug P of an idle cord circuit into the jack J of the calling line, which results in the operation of the sleeve relay 8 and in consequence the operation of the supervisory relay 10, in the manner already described. The operator then depresses the listening key to connect her telephone set to the calling line. It will be notedl that there may be a multiple connection from the operators telephone set to the calling end of the cord circuit through the dial key, which connection includes the dial sender. The operator then asks for the number ot' the wanted line and when she learns that this line terminates at a main exchange, inserts th-e plug P ot the calling'end of her cord circuit into the jack ot a trunk leading to the main automatic exchange. Either ot the trunk circuits, partially shown, in the drawing, may be 'used for this purpose. Let it be assumed that the plug P is inserted into the jack J 3 ot one ot these trunks. The operator presses vthe dial key and waits until a dialling tone yoperation of the springs, shunt springs 36 are closed to short-circuit the operators telephone set, so that no electrical disturbances resulting trom the opening and closing of impulse spring 35 will be heard by the operator. The impulses, due to the opening` of the impulse spring aretransn'iitted to the switches at the main exchange, over trunk conductor 37 through the tip contacts ot' the jack J3 and plug P', conductor 38, contacts 39 of the dial key, thence through the impulse spring 35, and shunt springs 36, contacts 4() of the dial key, conductor 41, ring contacts ot the plug P and jack J 3 and thence over the conductor 42 to the automatic switches at the main exchange. It will be noted that this impulse circuit has included in series therewith, the impedance 45, which serves at this stage to maintain the switches ot the connection operated.

In this connection, since there is no potential present on the vsleeve ot they jack J3, the sleeve relay 16 is not operated and consequently the calling supervisory relay A3 remains inactive. However, in order to provide supervision during this call, the relay 46 is bridged across the talking connection as follows: conductor 37, tip contacts oi the jackJ3 and plug P, through the normal contacts of the ringing key yand the dial key, conductor 47, armature and back contact ot relay 16, conductor 48, normal contacts 49 ot the thru dial key, conductorI 50, winding ot relay 46, conductor 51, inner back contact and armature otV relay 16` conductor 52, normal contacts 53 ot the dial key, normal contacts ot' the ringing keyconcuc tor 54, ring contacts of the plug P and jack J 3 to conductor 42 ot the selected trunk.

At the termination ot the conversation, when the calling subscriber at A replaces his receiver on its switch-hook, the answer-V ay A plul'all ly nl supervisory lump completed ut Commis of all of said relays while the answering end of the cord circuit is connect-ed to said trunk.

4. in a telephone system, a plurality of telephone lines, a trunk, cord circuits for connecting any telephone line with any other telephone line and ,with said trunk, an answering supervisory lamp and a calling supervisory lamp associated with each cord circuit, a supervisory relay associated with, but normally disconnected from the callingV end of each cord circuit, a sleeve relay'functioning to connect said supervisory relay to the calling end of its associated cord circuit,

an energizing circuit for said sleeve relay completed over the telephone line to which the calling end oil said cord circ-uit is connected, a third rela-y having an energizing circuit completed by the operation of said supervisory relay and said sleeve relay, a locking circuit for said third relay independent of said supervisory relay, a circuit including the calling supervisory lamp controlled by said supervisory relay and by said sleeve relay, and a circuit for the answering supervisory lamp controlled by all of said relays.

5. In atelephone system, a plurality of telephone lines, a trunk line, means including a cord circuit for connecting a telephone line with any other telephone line and with said trunk, asupervisory signal at each end of said cord circuit, a relay arranged to be operated when the answering end or" its cord circuit is connected to said trunk line, a supervisory relay associated with, but normally disconnected from the calling end of said cord circuit, a sleeve relay arranged when the calling end of said cord circuit is extended to a telephone line for connecting said supervisory relay to said cord circuit, a

tively separated but inductively connected f together by meansvot condenser-s, a manual key at each cord circuit for short-circuiting the condensers thereof, whereby an impulse sender can send impulses over its telephone line and through the cord circuit and trunk connected thereto, a supervisory relay ateach end of each cord circuit, but normally disconnected therefrom, a sleeve relay for each end of each cord circuit arranged to be operated in a. circuit including said cord t.

circuit and the telephone line to' which it is connected, each sleeve relay being arranged to be inactive when the end of the cord circuit with which it is associated is connected to said trunk, each sleeve relay serving to connect its associated supervisory relay with said cord circuit, the circuit of each sleeve relay being controlled at said manual key, and a supervisory signal controlled by each supervisory relay.

In witness whereof, I hereunto subscribe my name this 11 day of September, A. D. 1925. Y

JOHN H. Lnvrs, JR. 

